The present invention relates to ultrasonic diagnostic apparatuses and methods therefor.
A conventional ultrasonic diagnostic apparatus of this type has, as shown in FIG. 1, a transmission/reception means (1, 2, 3) for transmitting an ultrasonic pulse signal or ultrasonic continuous wave into a body under inspection; a reception means (1,4, 5) for receiving a reflected wave from a region to be diagnosed of the body under inspection and amplifying the received wave to generate a received wave signal; a focusing circuit (6, 7) coupled to receive the received wave signal amplified by the reception means for converging beams; a post-processing circuit (8) for compressing the received wave signal from the focusing circuit and detecting an envelope of the received wave signal; an image processing means (9, 10, 11) coupled to receive an output signal from the post-processing circuit 8 for converting this output signal from an analog form to a digital form and performing processing on the digital signal for displaying an image represented by this digital signal; and a display means (12, 13) coupled to receive an image signal from the image processing means for displaying an image represented by the received image signal. The apparatus of FIG. 1 is also provided with one or both of a transmitted wave weighting means for changing the amplitude or the like of transmitted pulses for each channel or for a unit of plural channels and a received wave weighting means for changing the amplitude of received wave signals. In FIG. 1, reference numeral 14 designates a frequency calculator constituting part of the image processing means coupled to receive an image signal representing an ultrasonic tomographic image from an image memory 11 for displaying the relationship between the luminance of the image signal in a region specified by the operator on a displayed still image and its frequency, and so on, for example, in graphical representation; and 15 a controller for controlling the operations of the respective components of the apparatus. This frequency calculator 14 is used to quantitatively display the ratio of characterizing points (points indicating lesions or the like) in a specified region, thus aiding the operator in performing diagnosis.
In FIG. 1, the received wave weighting means only is shown as the weighting means. This received wave weighting means is a weighting function generator 16 which receives a signal outputted from the controller 15 for switching the transmitter/receiver 1 in accordance with a depth, for example, and reads one of previously stored weighting functions corresponding to the kind of a selected transmitter/receiver 1. The weighting function generator 16 is composed of a storage means such as ROM for storing weighting functions therein and a latch for holding data for distributing a read weighting function to respective channels of received wave signals. A weighting function outputted from the weighting function generator 16 is converted into an analog signal by a D/A convertor (DAC) 17, and then delivered to pre-amplifiers 5 of the respective channels for amplifying received wave signal. Examples of conventional ultrasonic diagnostic apparatus having a transmitted or received wave weighting function are described in JP-A-3-222945, and JP-A-3-261466. It should be repeatedly noted that in conventional examples, a weighting function has previously been determined in accordance of the type of an employed transmitter/receiver.